.TH SLAPO-DATAMORPH 5 "RELEASEDATE" "OpenLDAP"
.\" Copyright 2016-2017 Symas Corp. All Rights Reserved.
.\" Copying restrictions apply.  See LICENSE.
.SH NAME
slapo\-datamorph \- store enumerated values and fixed size integers
.SH SYNOPSIS
olcOverlay=datamorph
.SH DESCRIPTION
The
.B datamorph
overlay to
.BR slapd (8)
allows attributes with a few pre-defined values to be saved more
space-efficiently as well as signed or unsigned integer attributes.

.LP
The overlay operates on configured attributes that must have their syntax
compatible with
.BR 1.3.6.1.4.1.4203.666.11.12.1.1 ,
there are three such syntaxes defined by the overlay:
.B 1.3.6.1.4.1.4203.666.11.12.1.2
(Enumerated value),
.B 1.3.6.1.4.1.4203.666.11.12.1.3
(Fixed-size integer), and
.B 1.3.6.1.4.1.4203.666.11.12.1.4
(Fixed-size signed integer).
.LP

While transforming the request, if a value for an attribute is not permitted by the configuration, the behaviour depends on the operation:

.RS
.TP
.B Search
The affected value assertions in a
.B Search
request filter are replaced by a filter returning
.B Undefined .
.TP
.B Compare
Request returns
.B Compare
.BR False .
.TP
.B Add, Modify
Requests are rejected with a
.B Constraint
.BR Violation .
.RE

The supported allowed matching rules for the attribute types above are:

.RS
.TP
.B EQUALITY fixedSizeIntegerMatch
Appropriate for syntaxes
.B 1.3.6.1.4.1.4203.666.11.12.1.2
(Enumerated value), and
.B 1.3.6.1.4.1.4203.666.11.12.1.3
(Fixed-size integer).
.TP
.B EQUALITY fixedSizeSignedIntegerMatch
Appropriate for syntax
.B 1.3.6.1.4.1.4203.666.11.12.1.4
(Fixed-size signed integer) only.
.TP
.B ORDERING fixedSizeIntegerOrderingMatch
Appropriate for syntaxes
.B 1.3.6.1.4.1.4203.666.11.12.1.2
(Enumerated value), and
.B 1.3.6.1.4.1.4203.666.11.12.1.3
(Fixed-size integer). Enumerated value attributes are compared according to
their stored database value.
.TP
.B ORDERING fixedSizeSignedIntegerOrderingMatch
Appropriate for syntax
.B 1.3.6.1.4.1.4203.666.11.12.1.4
(Fixed-size signed integer) only.


.SH CONFIGURATION LAYOUT

The overlay has to be instantiated under a database adding an entry of
.B olcOverlay=datamorph
with objectClass of
.BR olcDatamorphConfig.

The overlay configuration subtree consists of the following levels:
.RS
.TP
.B objectClass=olcDatamorphConfig
Main overlay configuration. Created directly under the database
configuration entry.
.TP
.B objectClass=olcDatamorphInteger
Specifies a
.B fixed-size integer
attribute and must be a child of an entry with
.BR objectClass=olcDatamorphConfig .
There may be as many such entries as necessary provided they all specify a
different attribute in the
.B olcDatamorphAttribute
attribute.
.TP
.B objectClass=olcDatamorphEnum
Specifies an
.B enumerated
attribute and must be a child of an entry with
.BR objectClass=olcDatamorphConfig .
There may be as many such entries as necessary provided they all specify a
different attribute in the
.B olcDatamorphAttribute
attribute.
.TP
.B objectClass=olcDatamorphEnumValue
Specifies a permitted value for the enumerated attribute and its database
representation. Must be a child of an entry with
.BR objectClass=olcDatamorphEnum .
There may be as many such entries as necessary provided they all specify a
different value and index in the corresponding fields.
.RE

In the case of
.BR slapd.conf (5),
the attribute definition is delimited by the keyword
.B datamorph
to define an integer or enumerated attribute followed by an arbitrary number of
.B datamorph_value
lines in the case of an enumerated one. Each new
.B datamorph
line starts configuring a new attribute.

.SH ENUMERATED ATTRIBUTE CONFIGURATION ENTRY

The enumerated attribute entry configuration
.RB ( olcDatamorphEnum )
only has the following option available:

.RS
.TP
.B olcDatamorphAttribute: <attribute>
Mandatory attribute, indicates that the named attribute is to be handled by the
overlay. The
.BR slapd.conf (5)
equivalent is
.B datamorph "int"
.BR <attribute> .
.RE

The children of this entry then define how the string values map to the
database values. They use the objectclass
.BR olcDatamorphEnumValue ,
which asks for the following attributes:

.RS
.TP
.B olcDatamorphValue: <value>
A permitted value for the attribute being configured.
.TP
.B olcDatamorphIndex: <0-255>
The corresponding database value.
.RE

The
.BR slapd.conf (5)
equivalent of the above two is
.B datamorph_value <0-255> <value>
.RB .

.SH FIXED-WIDTH INTEGER CONFIGURATION ENTRY

The fixed-width integer configuration entry
.RB ( olcDatamorphInteger )
has the following options available:

.RS
.TP
.B olcDatamorphAttribute: <attribute>
Mandatory attribute, indicates that the named attribute is to be handled by the
overlay. The
.BR slapd.conf (5)
equivalent is
.B datamorph "int"
.BR <attribute> .
.TP
.B olcDatamorphIntegerBytes: <1|2|4|8>
Size of the integer as stored in the backend. The
.BR slapd.conf (5)
equivalent is
.B datamorph_size
.BR <1|2|4|8> .
.TP
.B olcDatamorphIntegerSigned: <TRUE|FALSE>
Whether the integer is to be treated as signed. Note that the overlay will not
enforce consistency between this option and the attribute's syntax. The
.BR slapd.conf (5)
equivalent is
.B datamorph_signed
.BR <TRUE|FALSE> .
.TP
.B olcDatamorphIntegerLowerBound: <number>
The lowest value that the configured attribute will be allowed to have. This
affects all operations where values are mentioned. The
.BR slapd.conf (5)
equivalent is
.B datamorph_lower_bound
.BR <number> .
.TP
.B olcDatamorphIntegerUpperBound: <number>
The highest value that the configured attribute will be allowed to have. This
affects all operations where values are mentioned. The
.BR slapd.conf (5)
equivalent is
.B datamorph_upper_bound
.BR <number> .
.RE

.SH EXAMPLE

The following is an example of a configured overlay, substitute
.B $DATABASE
for the DN of the database it is attached to and
.B {x}
with the desired position of the overlay in the overlay stack.

.nf
dn: olcOverlay={x}datamorph,$DATABASE
objectClass: olcDatamorphConfig
olcOverlay: datamorph

# to handle attribute 'enumeratedAttribute'
dn: olcDatamorphAttribute=enumeratedAttribute,olcOverlay={x}datamorph,$DATABASE
objectClass: olcDatamorphEnum

# value 'value1' corresponds to 'AQ==' (0x01)
dn: olcDatamorphValue=value1,olcDatamorphAttribute={0}enumeratedAttribute,olcOv
 erlay={x}datamorph,$DATABASE
objectclass: olcDatamorphEnumValue
olcDatamorphIndex: 1

# value 'value11' corresponds to 'Cw==' (0x0B)
dn: olcDatamorphValue=value11,olcDatamorphAttribute={0}enumeratedAttribute,olcO
 verlay={x}datamorph,$DATABASE
objectclass: olcDatamorphEnumValue
olcDatamorphIndex: 11

# handle attribute 'signedInteger' as a 2-byte signed integer with values
# between -20000 and 30000 (inclusive on both sides)
dn: olcDatamorphAttribute=signedInteger,olcOverlay={x}datamorph,$DATABASE
objectclass: olcDatamorphInteger
olcDatamorphIntegerBytes: 2
olcDatamorphIntegerSigned: TRUE
olcDatamorphIntegerLowerBound: -20000
olcDatamorphIntegerUpperBound: 30000

# handle attribute 'shortInteger' as a 1-byte unsigned integer with only values
# 0 and 1 allowed (effectively a true/false)
dn: olcDatamorphAttribute=shortInteger,olcOverlay={x}datamorph,$DATABASE
objectclass: olcDatamorphInteger
olcDatamorphIntegerBytes: 1
olcDatamorphIntegerUpperBound: 1
olcDatamorphIntegerSigned: FALSE
.fi

The
.BR slapd.conf (5)
equivalent of the above follows:

.nf
overlay datamorph

datamorph enum enumeratedAttribute
datamorph_value 1 value1
datamorph_value 11 value11

datamorph int signedInteger
datamorph_size 2
datamorph_signed TRUE
datamorph_lower_bound -20000
datamorph_upper_bound 30000

datamorph int shortInteger
datamorph_size 1
datamorph_signed no
datamorph_upper_bound 1
.fi

.SH REPLICATION

Given that there are syntaxes and matching rules provided by the overlay, it
should be configured on each replica to guarantee consistency.

.SH BUGS AND LIMITATIONS
Due to the fact that overlays are not active in the
.BR slapcat (8)
nor
.BR slapadd (8)
processes, backups of the database will be made exactly as stored. This means
that backups made using
.BR ldapsearch (1)
cannot be used by
.BR slapadd (8)
nor can backups made using
.BR slapcat (8)
be loaded using
.BR ldapadd (8).

Value based ACLs that involve values of the transformed attributes are not
supported.

The overlay will refuse operations that add or rename entries with any of the
configured attributes in their RDN.

No controls are explicitly handled in the overlay, attaching any controls that
reference configured attributes might lead to unexpected behaviour and is
therefore discouraged.

Increment modification of the configured attributes is not supported either.

If a transformation is configured to be signed yet the attribute's schema uses the
unsigned syntax and matching rules, inequality matching will not work as
intended and will treat negative numbers as higher than positive numbers.

.SH FILES
.TP
ETCDIR/slapd.conf
default slapd configuration file
.TP
ETCDIR/slapd.d
default slapd configuration directory
.SH SEE ALSO
.BR slapd-config (5),
.BR slapd.conf (5),
.BR slapd.overlays (5),
.BR slapd (8),
.BR slapcat (8),
.BR slapadd (8)
.SH ACKNOWLEDGEMENTS
This module was developed in 2016 by Ondřej Kuzník for Symas Corp.
